As far as running passenger tires, that is what is used in the low profile trailers, but XL tires are used which have a stiffer sidewall than a P-metric passenger tire. Sidewall flexing generates heat, which, as I have said, kills tires.

Typically trailers have much more side to side sway, therefore more lateral pressure on the sidewalls than on a passenger vehicle, hence the recommendation for specific tires for trailers. Not that passenger tires might work for someone for years if they only do a short tow back and forth to a lake. But with a $30k boat sitting on the trailer, the extra couple hundred dollars every few years for trailer-specific tires is worth the piece of mind.

Consider also, if a tire ever did blow and cause damage as a result, I think the insurance company could get ornery if an investigation showed passenger tires were installed on the trailer.